/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/GenericPlatformApplicationMisc.h
If we know or can approximate the pixel density of the screen we will convert the incoming pixels to inches on the device. If the accuracy is unknown OutInches will be set to 0.
template<typename T, typename T2, typename [TEnableIf](API\Runtime\Core\Templates\TEnableIf)< [TIsFloatingPoint](API\Runtime\Core\Templates\TIsFloatingPoint)< T >::Value &&[TIsFloatingPoint](API\Runtime\Core\Templates\TIsFloatingPoint)< T2 >::Value, int >::type> static EScreenPhysicalAccuracy ConvertPixelsToInches ( T Pixels, T2 & OutInches )